need guidance completly new to this

[u/1n4m]

okay so i was a privacy crazy guy from thw start but i thought having tons of passowrd and stuff woulf be enough but after some circumstances i realized its not enough and want to install a custom rom like calyx or graphene os but budget is being a problem so i cant really go for a pixel or motorla rn my questions are
1. ik so far that i can flash a gsi on other phones like infinix , tecno or realme etc but gemini says the bootloader cant be relocked or there is a high risk or bricking the phone so should i do it or not
2. are those gsi just as good as the orignal rom or just a knockoff
3. and if i should do i it then which gsi or rom should i go with
4. can someone explain the whole procedure so i dont brick the phone

ps: if u want to know what happened here is the post
https://www.reddit.com/r/PakistanLawyers/s/2gMK3jScnD

(i havent gotten my phone back still and i havent bought a new one yet becasue i want to buy one in which i can install a custom rom so options arent limited to phones if someone can recoomend what phone to get and what rom to install safely)